1. Field of the Invention
The present invention relates to golf balls. In particular, the present invention relates to golf balls including a core and a cover.
2. Description of the Related Art
General golf balls include a core and a cover. For the cover, ionomer resin or polyurethane is used. The cover formed of ionomer resin has excellent resilience performance. On the other hand, the cover formed of polyurethane has excellent feel at impact, controllability, and scuff resistance.
JP-A-2002-336378 (US2003/64,831 and US2004/138,010) discloses a golf ball with a cover formed of a resin composition including polyurethane and a polyisocyanate compound. The polyisocyanate compound enhances the scuff resistance of the cover. Similar covers are disclosed in JP-A-H11-178949 (U.S. Pat. No. 6,123,628 and 6,582,325), JP-A-2002-336386 (US2003/064,832), and JP-A-2005-253962 (US2005/202,904).
A golf ball has numerous dimples on the surface thereof. The dimples enhance the lift force that acts upon the golf ball and reduce drag. The reduction of a drag and the enhancement of the lift force are referred to as a “dimple effect”. The dimple effect enhances the aerodynamic characteristic of the golf ball. In light of aerodynamic characteristic, various cross-sectional shapes of dimples have been proposed. JP-A-H11-89967 (U.S. Pat. No. 6,346,053) discloses dimples having a curvature radius at the edge in a range of 1 mm to 50 mm. JP-A-2000-279553 (U.S. Pat. No. 6,368,238) discloses dimples having a curvature radius at the edge in a range of 0.3 mm to 3.0 mm. JP-A-2005-230375 (US2005/187038) discloses dimples having a curvature radius at the edge in a range of 2.0 mm to 5.0 mm.
The golf ball is hit with golf clubs. The golf ball is required not to break even by the shock at impact. Further, the golf ball is required to be difficult to wear out even by frictional movement of the clubface thereagainst. Golf balls used at a driving range are repeatedly hit with golf clubs. The golf balls used at a driving range are particularly required to have excellent durability and wear resistance.
An objective of the present invention is to provide a golf ball having excellent durability and wear resistance.